I've been doing some Spice simulations of a single oscillator of the Lil Sidrassi paper circuit:

The main thing I discovered is that the 1Meg resistor also affects the frequency of the oscillator. So this can be replaced with a variable resistor (trimpot) or a normal pot.

I did a number of simulations for the different frequencies outlined on the paper circuit (mountain sub to ultrasound), with a number of different capacitor values and resistor values. Here's a table (the resistor values were 1Ohm to 1MegOhm). Interestingly, the different resistor values had no effect on Mountain or Subbubbass. mHz = milli Hertz!

Code: Select all

```
Description Hairy Capacitor Period Freq
Mountain sub 100uF 180s 5mHz
68uF 111s 9mHz
47uF 76s 13mHz
22uF 36s 27mHz
Subbubbass 10uF 16.5s 60mHz
6.8uF 11s 90mHz
4.7uF 7s 128mHz
2.2uF 3.2s 302mHz
Subbass 1uF 1.67s to 3.74s 578mHz to 600mHz
0.68uF 1.20s to 1.28s 781mHz to 829mHz
0.47uF 931ms to 3.4s 292mHz to 1.0Hz
0.22uF 408ms to 525ms 1.9Hz to 2.44Hz
Bass 0.1uF 182ms to 312 ms 3.2 to 5.5Hz
0.068uF 108ms to 287ms 3.47Hz to 9.25Hz
0.047uF 82ms to 97ms 10Hz to 12Hz
0.022uF 46ms to 222ms 4.5Hz to 21Hz
Treble 0.01uF 31ms to 174ms 5.5Hz to 31.6Hz
0.0068uF 107ms to 288ms 3.46Hz to 9.28Hz
0.0047uF 87ms to 97ms 10Hz to 12Hz
0.0022uF 45ms to 221ms 4.5Hz to 22Hz
Ultrasound 0.001uF 560us to 67ms 14Hz to 1.78kHz
0.00068uF 403us to 67ms 14Hz to 2.47kHz
0.00047uF 395us to 157ms 6Hz to 2.52kHz
0.00022uF 109us to 158ms 6.2Hz to 9kHz
Radio Ultrasound 0.0001uF 47us 21.3kHz @1Meg
```

Next step - breadboard it and see if it's correct that there is such a large range for the "Ultrasound" set of capacitors.